In a system of stack switches in a packet switched network, the switches are operatively interconnected via a pair of designated stack ports present on each switch. The system of stack switches is generally coupled in series and the topology of the system is generally characterized by a closed loop called a ring or an open strand of switches referred to herein as a chain. Each of the stack switches is adapted to perform switching between its own data ports as well as the data ports of other stack switches by transmitting packets via the stack ports using stack switch identifiers that facilitate the efficient transmission and switching of these packets to the appropriate stack switch. Presently, stack switches may be assigned switch identifiers manually configured by a user, for example. There remains a need for stack switches adapted to automatically and deterministically assign identifiers to participating switches ordinally, that is, in accordance with the order in which the switches are positioned in the ring or the chain.
Presently, stack switch systems are also vulnerable to duplicate identifier assignments that may occur where two stack switches from different systems are combined or where a user erroneously assigns the same identifier twice. In present systems, stack switches are automatically shut down which, unfortunately, can sever the connectivity across the system and create islands of stack switches. There remains a need for stack switches that are adapted to preserve the communication link between two neighboring switches without the switches having duplicate identifiers being able to forward packets within the stack switch system. In this case, there is also a need (1) to define criteria to select which of the switches will prevail as well as to maintain the active but non-operational switch in a state where it can still receive management commands; and (2) to resolve the conflict without manual intervention.
Presently, stack switch systems also employ message exchanges between the primary master stack switch and the managed stack switches to determine each other's operational status. Under certain circumstances, however, the primary master may not posses the computational resources to immediately respond to a status check in which case the managed devices may erroneously conclude that the primary master has failed and initiate the selection of a new primary master. As a result, a stack switch system may possess two primary masters resulting in system wide failure. There is, therefore, a need for stack switches that are adapted to cope with intermittent interruptions without prematurely initiating changes in system management.